1. Field of the Invention
The present application relates to polyimide powders, and more particularly to a colored polyimide powder used as a matting agent in a polyimide film.
2. Description of the Related Art
Flexible printed circuits (FPC) are widely used in electronic products, optical lens, LCD modulus, solar cells and the like. The flexible printed circuit usually includes a substrate or coverlay made of a polyimide film. These applications usually require that the polyimide film has low gloss, low transparency and good insulation. Low gloss allows the product to have a more aesthetic appearance, and insulation and low transparency can protect the printed circuit of the flexible printed circuit.
Generally, a matting agent and a colored additive (e.g., a pigment or a dye) are both used to fabricate the polyimide film. In a conventional fabrication process, a color additive (such as carbon black) is usually incorporated to reduce the transparency of the polyimide film, while a matting agent such as SiO2 may be added to reduce the gloss of the polyimide film. However, neither the colored additive nor the matting agent alone can achieve extinction and reduces transparency. Accordingly, the conventional fabrication process needs to use a large amount of the color additive and the matting agent to impart the desired properties to the polyimide film, which may cause problems such as difficult operations and poor dispersion of the additives.
Therefore, there is a need for a new approach that can fabricate a polyimide film with desirable characteristics in a cost-effective manner, and overcome the aforementioned issues.